Method for the Removal and Recovery of Metals and Precious Metals from Substrates

ABSTRACT

A method for removing metal and/or precious metal-containing depositions from substrates, wherein said substrate is subjected to treatment with an organo amine protectant component P and an inorganic active component A. Component P may be formed in situ by reaction with component R. Component P is an organic amine and/or organic amine hydrohalide and/or organic ammonium halide (preferably diisopropylamine hydrochloride), component A is an inorganic compound (preferably inorganic acid or a mixture thereof) and component R is an organic compound that can be split along the C—N bond by the component A into an organic amine (preferably dimethylformamide or N-methyl pyrrolidone). The metals in the form of organo-metallic complexes and/or metalorganic compounds are isolated and/or separated by means of different chemical reactions (preferably reduction reactions) and/or biosorption (preferably with seaweed or yeast). The isolated and/or separated organo-metallic complexes and/or metalorganic compounds are subjected to refinement process to form pure metals and/or pure precious metals. The substrates remain intact after the treatment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.61/575,976, filed Sep. 1, 2011 and application Ser. No. 14/241,105 filedFeb. 26, 2014, now U.S. Pat. No. 10,781,503, all of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

Traditionally it has been a challenge to remove thick and or multiplelayers of depositions of metals and precious metals from various typesof substrates. Current methods typically involve manually ormechanically removing depositions, including precious metal layers,which can damage substrates. Other methods can include the use ofaggressive or poisonous chemicals to remove the precious metals that canalso damage or destroy the substrate or that may not remove the entiredeposition from the substrate. Therefore, it was desirable to develop achemical method to remove layers of depositions, including preciousmetals, form various types of substrates.

Traditionally, separating different precious metals and metals has beena challenging if not impossible task. This has led to the loss ofprecious metals due to the lack of a viable method to separate then oncethey have been chemically changed from a metal to a compound insolution. Therefore, it was desirable to develop a chemical method toselectively remove metals and precious metals from a solution. Selectivebiomass sorption of metals and precious metals has been studied in theprior art. Hydrometallurgy 2010, 103, 180-189. Nilanjana, D.; Recoveryof Precious Metals Through Biosorption, deals with biosorption inrecovery of precious metals from aqueous solutions. The metal bindingmechanism, as well as the parameters influencing the uptake of preciousmetals and isotherm modeling, is presented. Biotechnology Advances 2007,25, 264-271, Mack, C.: Wilhelmi, B. Duncan, J. R., Burgess, J. E.;Biosorption of Precious Metals, reviews recent research regarding thebiosorption of some precious metals, with emphasis on the effects of thebiosorption environment and the biosorption mechanism identified.Biotechnology Advances 2006, 24, 427-451. Wang, J., Chen, C.;Biosorption of Heavy Metals by Saccharomyces cerevisae: A Review,elucidates the mechanism of metal uptake. Various mechanism assumptionsof metal uptake by S. cerevisiae are summarized. Kvasinky, Bachelor'sthesis, Marketa Novakova, 2010, deals with Saccharomyces cerevisiae, andsummarizes cell biological study, and its genome, reproduction, growthconditions, and metabolism.

STATEMENT OF THE INVENTION

This invention concerns use of organo amines, to protect a substratefrom damage during the removal of a deposition consisting of one or morelayers of metal and/or precious metals adhered to the substrate. Once insolution, it is disclosed in this invention to use certain types ofreduction methods and/or biomass materials to extract and separate thedifferent types of metals and/or precious metals. The use of inorganicnitrogen compounds is also contemplated for use with the presentinvention.

The invention provides a method to remove depositions, including metalsand precious metals such as gold and/or platinum and/or silver and/orpalladium and/or indium, from a substrate without damaging the substrateand/or efficiently extract it from different substrates.

The invention would be a suitable replacement for aqua regia, a knownpowerful acid traditionally used to recovery gold and platinum.Additionally, the invention provides a method for theremoval/extraction/separation of metals and precious metals fromdifferent abrasive blasting media and from solutions of mixtures ofmetals and precious metals, from ores, and from other sources.

The invention will allow for the recovery of gold, platinum, silver,palladium, indium and other metals and precious metals utilizing achemical method of stripping, separation, and purification fromdifferent substrates that results in high yields and purity whilepreserving the substrates. The invention may be used either in a batchprocess for treatment of discrete materials with coatings or in acontinuous process for materials in long rolls. The invention has thepotential to offer “green technology” by allowing the recovery andrecycling of substrates, especially polymeric substrates that arenormally destroyed when recovering precious metals and by avoiding theuse of poisonous chemicals (cyanides for instance) while extracting goldand platinum from ores.

The invention consists of two chemical constituents: a PROTECTANT “P”and an ACTIVE chemical “A” that function to remove a layer and/ormultiple layers of depositions, including metals and/or precious metals,from various types of substrates while not damaging the substrate.PROTECTANT agent “P” functions in the reaction as a surface protectantfor the substrate. Additionally, PROTECTANT agent “P” can function as aCOMPLEXING agent “C” with metals that are oxidized and/or form othermetal compounds. The PROTECTANT agent “P” may be added to the reactiondirectly or created in situ by the chemical reaction between REAGENT “R”and the ACTIVE chemical “A”. Since the PROTECTANT agent “P” protects thesurface of the substrate, it allows the ACTIVE chemical “A” to be achemical or mixture of chemicals (such as aqua regia) that wouldotherwise damage the substrate while dissolving or separating theprecious metals from the substrate.

It has turned out that the protectant function according to theinvention is best performed by mono-, di-, tri-substituted amines and/ortheir hydrohalides and/or tetra-substituted ammonium halides, whereineach substituent is independently an alkyl, a cycloalkyl or asubstituted alkyl. The term “alkyl” as used herein means an aliphaticlinear or branched group having 1 to 18 carbon atoms. The term“cycloalkyl” herein means a cyclic aliphatic group having 3 to 8 carbonatoms. The term “substituted alkyl” as used herein means an aliphaticlinear or branched group having 1 to 18 carbon atoms substituted bydifferent functional groups, such as hydroxy-group and/or carboxy-groupand/or hydroxy and carboxy group,

Examples of surface PROTECTANT “P”/COMPLEXING agent “C” chemical includethe organo-amines such as trimethylamine hydrochloride ((CH₃)₃N.HCl),dimethylamine hydrochloride ((CH₃)₂NH.HCl), methylamine hydrochloride(CH₃NH₂.HCl), triethylamine hydrochloride ((CH₃CH₂)₃N.HCl),dimethylamine hydrochloride ((CH₃CH₂)₂NH.HCl), methylamine hydrochloride(CH₃CH₂NH₂.HCl), cyclohexylamine hydrochloride (C₆H₁₁NH₂.HCl),dicyclohexylamine hydrochloride ((C₆H₁₁)₂NH.HCl),N,N-dimethylcyclohexylamine hydrochloride (C₆H₁₁N(CH₃)₂.HCl),diisopropylamine hydrochloride ((CH₃)₂CHNHCH(CH₃)₂.HCl),N-ethylcyclohexylamine hydrochloride (C₆H₁₁NC₂H₅.HCl),N-methylcyclohexylamine hydrochloride (C₆H₁₁NCH₃.HCl), glycine betainehydrochloride (CH₃)₃N⁺CH₂COOH.Cl⁻, choline chloride [(CH₃)₃NCH₂CH₂OH]Cl,carnitine hydrochloride (CH₃)₃N(Cl)CH₂CH(OH)CH₂COOH, tetraethylammoniumbromide [(CH₃CH₂)₄N]Br, tetra-n-butylammonium fluoride(CH₃CH₂CH₂CH₂)₄NF, methylamine hydroiodide (CH₃NH₂.HI), etc.

Examples of REACTIVE “R” surface protectant/COMPLEXING “C” agents thatcan form amines in situ include dimethylformamide (DMF)-C₃H₇NO) andN-methyl pyrrolidone (NMP)-C₅H₉NO, and other organic compounds (such asamides and/or lactams) that can be split along the C—N bond into anamine and other organic compound (such as dimethylamine and formic acidin case of DMF).

Examples of ACTIVE chemical “A” include inorganic acids and mixturesthereof from the group consisting of nitric acid (HNO₃) and/orhydrofluoric acid (HF), and/or hydrochloric acid (HCl) and/or phosphoricacid (H₃PO₄), and/or fluorosilicic acid (H₂SiF₆), and/or ammoniumperoxydisulfate ((NH₄)₂S₂O₈), and/or sulfuric acid (H₂SO₄), and otherinorganic compounds that can cause splitting organic compounds (such asamides and/or lactams) along the C—N bond into organic amine(s) andother organic compounds and/or can dissociate any amine hydrochlorideinto the PROTECTANT “P” and COMPLEXING agent “C” to allow its dualaction (protecting and complexing).

Examples of substrates include aluminum, copper, steel, stainless steel,glass, titanium, their alloys, graphite, carbon fibre, ceramic, fusedsilica, quartz, blasting media (such as corundum, sand, corn cob,plastic abrasives, silicon carbide, pumice, steel grit, steel shot,walnut shells, soda, and glass beads), polymers (such as PEEK, PET,polyimide, polyether, etc.) and ores.

The following equations illustrate the two chemical reaction mechanisms:

[Deposition on Substrate]+P/C+A→Deposition (in solution) or Deposition-C(in solution)+Substrate-P+Solution[Deposition on Substrate]+R/C+A→Deposition (in solution) or Deposition-C(in solution)+Substrate-P+Solutionwhere Deposition=one or more selected from Be, Mg, Ca, Ti, Zr, V, Nb,Ta, Cr, Mo, W, Mn, Fe, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In,Tl, C, Si, Sn, N, P, As, S, Se, Te, and their mixtures, and/or theirchemical compounds.

Once the depositions have been separated from the substrate anddissolved and/or extracted into solution, separating the differentprecious metals has traditionally been a challenging if not impossibletask. One method to remove metals from solution is the use of biomassmaterials to selectively biosorb reaction products that were originatedin situ by chemical reactions between the deposition and/or “P” and/or“R” and/or “A”. The use of biomass materials allows one to reclaimmetals and/or precious metals that would have otherwise been difficultand/or unsafe to separate. Specifically, certain types of biomassmaterials are able to bind and concentrate metals from aqueoussolutions. A biosorption-based process offers a number of advantagesincluding low cost, selective metal reclamation, high efficiency inmetal complexation and high purity of the final metal.

This invention consists of using selected biosorbants to recover metalsand/or precious metals and/or their chemical compounds. Examples ofselective biosorbants include seaweed (ie Spirulina platensis) and yeast(i.e. Saccharomyces cerevisiae).

The following equations illustrate the selective chemical reactionmechanisms:

[Mixture of M's (X,Y,Z)] (in solution)+Bioadsorbant (I)→[M(X)+Bioadsorbant]+[Mixture of M's (Y,Z)] (in solution[Mixture of M (X,Y,Z)] (in solution)+Bioadsorbant (II)→[M(Y)+Bioadsorbant]+[Mixture of M's (X,Z)] (in solution)where M=Metals and/or Precious Metals and/or their chemical compoundsX,Y,Z=Mixture of Metals and/or Precious Metals and/or their chemicalcompounds

BRIEF DESCRIPTION OF FIGURES

FIG. 1 depicts an apparatus for recovering gold from a PET substrate.The PET substrate is provided in spooled rolls.

FIGS. 2 and 3, the gold-hued PET is fed from the roll to a first stationwhere it is soaked in a cleaning solution that was made in accordancewith the teachings of the present invention.

FIG. 4, the substrate is passed from the first station to a secondstation that is filled with water. By passing the substrate through thesecond station, the majority of the solution from the first station isremoved.

FIG. 5, the substrate is passed through a series of rollers to removethe rest of the cleaning solution and subsequently passed through awater mist. The liquids from all stations are subjected to a goldrecovery process including reduction.

FIG. 6, the illustrated rolls are 425 meters long and two such rolls canbe processed in approximately 90 minutes in the illustrated continuousprocess.

FIG. 7, approximately 187 g of gold are recovered for every 100 kg ofthe PET substrate.

FIG. 8 illustrates a batch process for cleaning a substrate andrecovering the gold plating. Gold-plated substrates are soaked in acleaning solution that was made in accordance with the teachings of thepresent invention. Before submersions, the sheets have a metallic hue.

FIG. 9, after briefly soaking the substrate, the metallic hue is goneand the substrate is white.

FIG. 10 provides a depiction of one submerged substrate (white) and onepre-treated substrate (metallic).

FIG. 11, after soaking, the residual cleaning solution is removed fromthe substrate by rising with water.

FIG. 12 depicts the cleaned, white substrate. The gold layer was removedwithout damaging the substrate, including notes that were written on thesubstrate.

FIG. 13 provides another depiction of the metallic substrate prior totreatment.

FIG. 14 depicts an aqua regia solution dissolving a copper substrate.The copper wire gets dissolved within 40 minutes.

FIGS. 15 and 16 illustrates the addition of DMF to the aqua regiasolution and the subsequent inability of the DMF solution to rapidlydissolve the copper wire (FIG. 16). The copper wire stays intact longenough until the aqua regia dissolves a possible deposition.

FIG. 17 depicts a copper part plated with gold, platinum and titanium.After two days of soaking in the inventive cleaning solution followed bybrush cleaning, the majority of the metal layer was removed withoutdamaging the copper.

FIGS. 18 and 19, the copper part is intact, i.e. the aqua regiaselectively etched the deposition only, while DMF served as surfaceprotectant.

FIG. 20 depicts an aluminum part plated with SiOx deposits. In order toetch the SiO_(x) the aluminum part was treated with DMF and a mixture ofphosphoric acid and hydrofluoric acid (where the organo-amine is formedin-situ).

FIG. 21, a layer of black material was visible on the surface of thealuminum which was rinsed away with water.

FIG. 22 depicts the aluminum part undamaged from this treatment method.Without wishing to be bound to any particular theory, applicant believesthis black material is a protective layer that prevents damage to thealuminum part.

FIGS. 23-27 depict that a multilayer deposition of gold, platinum,titanium, and aluminum has been dissolved and removed from a stainlesssteel substrate using an organo-amine and nitric acid. FIG. 23 depictsparts feeding into the reaction mixture (etching solution). The ratio ofchemicals stays the same every time a fresh solution is prepared. All 4of the metals were successfully dissolved/removed from the stainlesssteel substrate without damage to the substrate (FIG. 27).

FIG, subsequently, the gold was separated from the platinum, titanium,and aluminum using gold reduction methods; addition of the reducingagent;

FIG. 29 shows filtration of the solution with gold powder;

FIG. 30-31 shows cleaning the melted gold's surface from residues), andpurified to 99.99% minimum purity;

FIGS. 31-34 show the platinum was separated from the titanium/aluminumsolution using a biosorption method (for example, using yeast, FIGS. 32through 34).

EXAMPLES Example 1—Comparative

A sample of nitric acid (50%) and hydrochloric acid (31%) was prepared(1:1 volume ratio). Several pieces of copper wire were added to thissolution. The copper wire completely dissolved within 40 minutes.

Example 2

A 20 mL sample of nitric acid (50%) and 20 mL hydrochloric acid (31%)was prepared in 200 mL N,N-dimethylformamide (DMF). Several pieces ofcopper wire were added to this solution. The copper wire showed no signsof dissolving within 40 minutes.

Example 3

A sample of 100 mL nitric acid (50%) and 300 mL hydrochloric acid (31%)was prepared in 4 L N,N-dimethylformamide (DMF). A solid piece of copperwas coated with an alloy of gold, platinum and titanium. The copper wassoaked in the sample solution for fourteen days at room temperature. Thecopper was removed from the solution and rinsed and manually washed toremove residual protective coating. The resulting copper appeared freeof gold, platinum and titanium. There was no visible damage to thecopper.

Example 4—Comparative

A sample of phosphoric acid (50%) and hydrofluoric acid (50%) wasprepared. A piece of aluminum foil was added to this solution. Thealuminum completely dissolved within 20 minutes.

Example 5

A sample of 25 mL phosphoric acid (50%) and 25 mL hydrofluoric acid(50%) was prepared in 400 mL N,N-dimethylformamide (DMF). A piece ofaluminum foil was added to this solution. The aluminum showed no signsof dissolving within 20 minutes.

Example 6

A sample of 30 L phosphoric acid (50%) and 30 L hydrofluoric acid (50%)was prepared in 200 L N,N-dimethylformamide (DMF). A sheet of aluminumwas coated with a SiOx deposition. The aluminum was soaked in the samplesolution for ten days at room temperature. The aluminum was removed fromthe solution and rinsed and manually washed to remove residualprotective coating. The resulting aluminum appeared free of the SiOxdeposits. There was no visible damage to the aluminum.

Example 7

A gold-coated polyethylene terephthalate (PET) substrate (57.6 kg) wasprovided as a rolled thin-film. The film was sequentially rolled throughthe solution 50 L of nitric acid (50% diluted) and 3.5 kg oftrimethylamine hydrochloride at a rate of about 9 meters per minute. Thefilm was rinsed under a stream of water to remove trace acid. Afterprocessing, the gold-color was no longer visible on the film and thecleaning agents were gold-colored. There was no visible damage to thePET substrate.

Example 8

A provided stainless steel substrate coated with gold, platinum,titanium and aluminum (44 parts of different weights and sizes) wassubmerged into an etching mixture of 240 L of nitric acid (50%) and 16kg of trimethylamine hydrochloride. All layers of gold, platinum,titanium, and aluminum dissolved in the etching mixture within 3 hoursto 30 days depending on the thickness of the layers. There was novisible damage to the stainless steel parts. The solution wassubsequently subjected to a reduction and refinement process thatseparated the gold from the other metals and refined the gold to 99.99%minimum purity. To the remaining solution containing platinum, titanium,and aluminum yeast (Saccharomyces cerevisiae) was added in the ratio of1 kg of yeast per 200 liters of the solution. The organo-platinumcomplex and/or metalorganic compound of platinum was left to selectivelybioadsorb onto the yeast for one day to successfully separate theplatinum from the other metals. Then yeast/organo-platinum adsorbate mixwas then filtered off and burned at 1500° C. The remaining platinumoxide was isolated, pressed into pellets, and vacuum melted intoplatinum metal.

Example 9

The gold containing solutions of example 7 and 8 were subjected to areduction and refinement protocol to provide 99.99% minimum puritygold—107.75 g of gold (187 g Au per 100 kg of the PET strip). Thefollowing describes the reduction and refinement protocol.

Example 10—Comparative

Three pieces of gold of similar shape, each 30 grams, were submergedinto three etching mixtures. Each mixture consisted of 15 liters ofnitric acid (50%) and (1) 1 kg of trimethylamine hydrochloride, (2) 1 kgof dimethylamine hydrochloride, (3) 1 kg of methylamine hydrochloride.The speed of gold dissolutions were measured over the period of twoweeks and compared. The experiments suggested that the aminehydrochloride ability to dissolve and/or etch gold decreases in thetrimethylamine hydrochloride>dimethylamine hydrochloride>methylaminehydrochloride order. The speeds were: 0.81 g>0.65 g>0.52 g of goldweight loss per day (room temperature, no stirring).

Example 11—Comparative

Five pieces of gold of similar shape, each 30 grams, were submerged intofive etching mixtures. Each mixture consisted of 15 liters of nitricacid (50%) and (1) 1 kg of triethylamine hydrochloride, (2) 1 kg ofdiisopropylamine hydrochloride, (3) 1 kg of N-ethylcyclohexylaminehydrochloride, (4) 1 kg of dibutylamine hydrochloride and (5) 1 kg oftrimethylamine hydrochloride. The speed of gold dissolutions weremeasured over the period of two weeks and compared. The experimentssuggested that the amine hydrochloride ability to dissolve and/or etchgold decreases in the diisopropylamine hydrochloride>dibutylaminehydrochloride>triethylamine hydrochloride>N-ethylcyclohexylaminehydrochloride>trimethylamine hydrochloride order. The speeds were: 2.03g>1.78 g>1.53 g>1.51 g>0.81 g of gold weight loss per day (roomtemperature, no stirring).

Example 12—Comparative

Two pieces of gold of similar shape, each 30 grams, were submerged intotwo etching mixtures. Each mixture consisted of 15 liters of nitric acid(50%) and (1) 1 kg of N-ethylcyclohexylamine hydrochloride, purchasedcommercially, and (2) 1 kg of N-ethylcyclohexylamine hydrochloride,prepared in situ by mixing appropriate amounts of N-ethylcyclohexylamineand hydrochloric acid, followed by adding the nitric acid. The speed ofgold dissolutions were measured over the period of two weeks andcompared. The speeds were: 1.51 g/1.50 g per day (room temperature, nostirring). The experiments suggested that there is no difference inability to dissolve and/or etch gold between the commercial and in situprepared chemical.

Example 13

A gold-, silver-, indium-coated ethylene vinyl acetate (EVA) substrate(30 kg) was provided as a rolled thin-film. The film was sequentiallyrolled through the solution 25 L of nitric acid (50% diluted) and 1.5 kgof carnitine chloride at a rate of about 6 meters per minute. The filmwas rinsed under a stream of water to remove trace acid. Afterprocessing, there was no visible damage to the EVA substrate. Thedark-color was no longer visible on the EVA film and the etching agentswere yellow-colored and there was a visible precipitate of a silversalt. The silver salt was removed from the solution, rinsed, washed andsubjected to refinement process to deliver silver in 99.9 minimumpurity. The remaining solution containing indium and gold wassubsequently subjected to a reduction and refinement process thatseparated the gold from indium and refined the gold to 99.99% minimumpurity. The remaining solution containing indium was subsequentlysubjected to a treatment with sodium hydroxide (NaOH) and formic acid(HCOOH). The precipitate of an indium complex and/or metalorganiccompound of indium was subsequently subjected to refinement process toobtain the indium in 99.9% minimum purity. The yields of silver, goldand indium were quantitative.

Example 14

A provided stainless steel substrate coated with gold, platinum,palladium, nickel, copper, and zinc was submerged into an etchingmixture 6 L of nitric acid (50% diluted) and 0.5 kg of glycine betainehydrochloride. All layers of gold, platinum, palladium, nickel, copper,and zinc dissolved in the etching mixture within 3 hours. There was novisible damage to the stainless steel substrate. The solution wassubsequently subjected to a reduction and refinement process thatseparated the gold from platinum and palladium and from nickel, copper,and zinc, and refined the gold to 99.99% minimum purity. To theremaining solution containing platinum, palladium, nickel, copper, andzinc yeast (Saccharomyces cerevisiae) was added in the ratio of 0.05 kgof yeast per 10 liters of the solution. The organo-platinum complexand/or metalorganic compound of platinum was left to selectivelybioadsorb onto the yeast for one day to successfully separate theplatinum from the other metals. The yeast/organo-platinum adsorbate wasthen filtered off and burned at 1500° C. The remaining platinum oxidewas isolated, pressed into pellets, and vacuum melted into platinummetal. The remaining solution containing palladium, nickel, copper, andzinc was subsequently subjected to a treatment with sodium hydroxide(NaOH) and acetic acid (CH₃COOH). The precipitate of a palladium complexand/or metalorganic compound of palladium was subsequently subjected torefinement process to obtain the palladium in 99.9% minimum purity. Theyields of gold, platinum and palladium were quantitative.

Example 15

A provided ceramic substrate coated with indium, iron, arsenatevanadium, magnesium, calcium, chromium, yttrium, thallium and manganese,was submerged into an etching mixture 6 L of nitric acid (50% diluted)and 0.5 kg of tetraethylammonium bromide. All layers of indium, iron,arsenate, vanadium, magnesium, calcium, chromium, yttrium, thallium andmanganese, dissolved in the etching mixture within 3 hours. There was novisible damage to the ceramic substrate. The solution containing indium,iron, arsenate vanadium, magnesium, calcium, chromium, yttrium, thalliumand manganese was subsequently subjected to a treatment with sodiumhydroxide (NaOH) and formic acid (HCOOH). The precipitate of an indiumcomplex and/or metalorganic compound of indium was subsequentlysubjected to refinement process to obtain the indium in 99.9% minimumpurity. The yield of indium was quantitative.

Example 16

A provided glass substrate coated with palladium, beryllium, zirconium,niobium, tantalum and molybdenum was submerged into an etching mixture 6L of nitric acid (50% diluted) and 0.5 kg of methylamine hydroiodide.All layers of palladium, beryllium, zirconium, niobium, tantalum andmolybdenum dissolved in the etching mixture within 3 hours. There was novisible damage to the glass substrate. The solution containingpalladium, beryllium, zirconium, niobium, tantalum and molybdenum wassubsequently subjected to a treatment with sodium hydroxide (NaOH) andacetic acid (CH₃COOH). The precipitate of a palladium complex and/ormetalorganic compound of palladium was subsequently subjected torefinement process to obtain the palladium in 99.9% minimum purity. Theyield of palladium was quantitative.

Example 17

A provided blasting sand with gold, carbide, yttrium, tungsten, gallium,sulfate and selenium was submerged into an etching mixture 6 L of nitricacid (50% diluted) and 0.5 kg of tetra-n-butylammonium fluoride. Gold,carbide, yttrium, tungsten, gallium, sulfate and selenium dissolved inthe etching mixture within 3 hours. The solution was subsequentlysubjected to a reduction and refinement process that separated the goldfrom the other metals and refined the gold to 99.99% minimum purity. Theyield of gold was quantitative.

Example 18

A provided carbon fiber precision parts coated with silver, cadmium,borate, silicon, tin, nitride, phosphate and tellurium was submergedinto an etching mixture 6 L of nitric acid (50% diluted) and 0.5 kg ofcholine chloride. All layers of silver, cadmium, borate, silicon, tin,nitride, phosphate and tellurium dissolved in the etching mixture within3 hours. There was no visible damage to the carbon fibre precisionparts. A precipitate of a silver salt was visible in the solution afterthe etching. The silver salt was removed from the solution, rinsed,washed and subjected to refinement process to deliver silver in 99.9minimum purity.

Reduction and Refinement of Gold Recovered from a Substrate

Once the gold has been removed from a substrate and is in solution as acomplex and/or metalorganic compound, it must then be reduced throughchemical treatment to form elemental gold.

Reduction of the gold is accomplished as follows. Dilute the goldsolution with between 60% to 80% by volume of the solution withdistilled water. Then add a saturated aqueous solution of urea(H₂NCONH₂) to the diluted solution of gold (5 kg per 250 liters ofsolution) to destroy the nitric acid, HNO₃. Neutralization of thesolution is determined by standard methods such as pH, titration,visual, or by other methods. Once the solution has been neutralized,hydroxylamine hydrochloride, NH₂OH.HCl, is added to the solution at roomtemperature. Addition of the hydroxylamine hydrochloride is done in 5 kgquantities until all of the gold has been precipitated from solution.Likewise, the hydroxylamine hydrochloride is added in 5 kg quantities soas to avoid any hazards in adding too much of the reducing agent tooquickly. The presence of gold in the solution is tested on a smallsample of solution using tin chloride, SnCl₂. If gold is still present,a dark brown/black precipitate will form with the addition of tinchloride. If no gold is present, the color of the solution will stay thesame and be free of precipitate. Once all of the gold has beenprecipitated from solution, most of the solution is decanted from thegold precipitate, the gold is then filtered through a standard filterpaper, and rinsed with distilled water during filtration. The recoveredgold powder and filter paper are dried at 120-130 C for 4 hours in astandard convection oven. The gold powder is weighed after it is fullydried, and all gold is removed from the filter paper, using a wire brushif necessary to get as much gold as possible from the paper. The goldpowder is now transferred to a melting crucible, mixed with anhydroussodium tetraborate (Na₂B₄O₇), two teaspoons of borax per 200 grams ofgold powder, and heated to 1180° C. for 5 to 10 minutes. The crucible iscooled in water and destroyed so as to remove the gold. The recoveredgold “Roundlet” is boiled in nitric acid (12M, diluted by 50%, 2 hoursminimum), rinsed with distilled water, air dried, weighed, rinsed withisopropyl alcohol, and air dried a final. The gold is now 99.99% minimumpurity.

Similar results have been obtained using other alkylamine and/orcycloalkylamine and/or substituted alkylamine hydrohalides and/oralkylammonium and/or cycloalkylammonium and/or substituted alkylammoniumhalides as protectant and/or complexing component.

1. A method for removing metal and precious metal-containing depositionsfrom a substrate, comprising the step of (i) treating the substrate withan organo amine protectant component (“P”) and an inorganic activecomponent (“A”) or (ii) treating with a complexing component (“C”) andan “A”, wherein said component “P” or “C” is selected from the groupconsisting of mono-substituted amine hydrohalides, di-substituted aminehydrohalides, tri-substituted amine hydrohalides, and tetra-substitutedammonium halides, wherein each substituent is independently an alkylhaving 1 to 18 carbon atoms or a cycloalkyl having 3 to 8 carbon atomsor an alkyl having 1 to 18 carbon atoms substituted by hydroxy-group oran alkyl having 1 to 18 carbon atoms substituted by carboxy-group or analkyl having 1 to 18 carbon atoms substituted by hydroxy and carboxygroup, and wherein said component “A” is an inorganic acid, a salt of aninorganic acid, or a mixture thereof.
 2. The method of claim 1, whereinsaid halide is chloride or fluoride or bromide or iodide.
 3. The methodof claim 1, wherein said organo amine protectant is prepared in situ byreaction of an organic amine and hydrochloric- or hydrofluoric- orhydrobromic- or hydroiodic-acid.
 4. The method of claim 1, wherein saidcomponent “P” or “C” is selected from the group consisting oftriethylamine hydrochloride, diethylamine hydrochloride, ethyl aminehydrochloride, cyclohexylamine hydrochloride, dicyclohexylaminehydrochloride, N,N dimethylcyclohexylamine hydrochloride,diisopropylamine hydrochloride, N ethylcyclohexylamine hydrochloride andN-methylcyclohexylamine hydrochloride, glycine betaine hydrochloride,choline chloride, carnitine chloride, tetra-n-butylammonium fluoride,tetraethylammonium bromide, methylamine hydroiodide.
 5. The method ofclaim 1, wherein said component “P” or “C” is selected from the groupconsisting of trimethylamine hydrohalide, dimethylamine hydrohalide andmethylamine hydrohalide.
 6. The method of claim 1, wherein saidcomponent “P” or “C” is formed in situ by reaction of said component “A”with a reactive component “R”.
 7. The method of claim 5, wherein saidcomponent “R” is selected from the group consisting of organic amidesand organic lactams.
 8. The method of claim 6, wherein said component“R” is dimethylformamide or N-methylpyrrolidone.
 9. The method of claim1, wherein said component “A” is aqua regia.
 10. The method of claim 1,wherein said component “A” is selected from the group consisting ofnitric acid, hydrofluoric acid, hydrochloric acid, phosphoric acid,hexafluorosilicic acid, ammonium peroxydisulfate and sulfuric acid andmixtures thereof.
 11. The method of claim 1, wherein said depositioncomprises at least one material selected from the group consisting ofBe, Mg, Ca, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ni, Pd, Pt, Cu, Ag,Au, Zn, Cd, B, Al, Ga, In, Ti, C, Si, Sn, N, P, As, S, Se, Te, theirmixtures, and their chemical compounds.
 12. The method of claim 1,wherein said substrate comprises at least one material selected from thegroup consisting of aluminum, copper, steel, stainless steel, glass,titanium, aluminum alloys, copper alloys, steel alloys, stainless steelalloys, titanium alloys, graphite, carbon fiber, ceramic, fused silica,quartz, polymers, ores and blasting media selected from the groupconsisting of: corundum, sand, corn cob, plastic abrasives, siliconcarbide, pumice, steel grit, steel shot, walnut shells, soda and glassbeads.
 13. The method of claim 1, wherein said metal is recovered fromthe solution resulting from said treatment.
 14. The method of claim 13,wherein said recovery is carried out by means of a biosorbant.
 15. Themethod of claim 14, wherein said biosorbant is selected from seaweed andyeast.
 16. The method of claim 15, wherein the biosorbant is Spirulinaplatensis.
 17. The method of claim 15, wherein the biosorbant isSaccharomyces cerevisiae.
 18. The method of claim 13, wherein saidrecovery is carried out by means of a reducing agent.
 19. The method ofclaim 18, wherein the reducing agent is hydroxylamine hydrochloride,glucose, sodium bisulfite, sulfur dioxide.
 20. The method of claim 13,wherein said recovery is carried out by means of an organic acid. 21-37.(canceled)